This invention relates to a circuit arrangement for interruption-free switching of a voltage to an output terminal, in which feed voltages are supplied to two input terminals and in which it is intended to switch to the higher of the two feed voltages.
Such switches are needed, for example, when the supply voltage of C-MOS memories must be switched from AC to battery operation or vice versa. In present day commercial devices, relay circuits are used for this purpose. These have a certain sluggishness, however, and switching does not occur without interruption of the supplied voltage. In addition, these relay circuits require a supplementary drive circuit. Known also are switches using diodes whose cathodes or anodes are connected to one another and to an output terminal. Because of the diode threshold voltage of about 0.7 V, these switching systems, even at small currents, necessarily involve a voltage drop which is greater than the value which is permissible, for example, in the current supply of integrated semiconductor components, such as C-MOS memories.
It is an object of this invention to provide a circuit arrangement meeting the above described need in a simple manner.